What Does DGA Reveal About Newly Installed Transformers?
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- What Does DGA Reveal About Newly Installed Transformers?
This is Part 1 of a two-part series on using dissolved gas analysis to detect early faults in transformers. Here we will address the importance of early DGA sampling during the first month of a new transformer’s service life. In Part 2, we will discuss the next critical diagnostic milestone — the first routine in-service monitoring interval — commonly referred to as the Ten-Month Full-Oil Test.
Why New Transformers Still Fail
New transformers are not immune to defects. While a unit that survives initial energization and the first several minutes of operation is statistically likely to perform reliably over the long term, manufacturing defects can still be present — and may not manifest immediately. When these defects develop into faults, they typically leave characteristic dissolved gases in the insulating oil. Dissolved gas analysis (DGA) is the primary diagnostic tool for detecting these fault signatures early, often before the fault progresses far enough to cause permanent damage.
DGA as a Warranty Requirement
Transformer manufacturers commonly prescribe a structured initial testing schedule that includes DGA, particularly during the first month of service — and in some cases, longer. This schedule is not merely a best-practice recommendation. In many cases, adherence to the specified testing protocol is a condition of warranty validity. Failing to conduct required DGA tests within the prescribed intervals can void manufacturer coverage, shifting the financial and operational risk of a defect-related failure entirely to the asset owner.
The First 30 Days: The Critical Window
Even when a manufacturer does not specify a formal testing requirement, DGA during the first 30 days in service provides meaningful diagnostic value. This period represents the highest-risk window for latent manufacturing defects to surface under operating conditions. Early testing during this window can:
- Identify incipient faults while they are still developing and corrective action remains viable
- Minimize damage to the transformer itself, preventing a manageable fault from becoming a catastrophic failure
- Reduce consequential damage to connected equipment and the broader system
- Limit lost production resulting from unplanned outages
Prevention vs. Recovery
Even when a transformer failure is covered under warranty — meaning the manufacturer bears responsibility for repair or replacement — the downstream costs of an actual failure often extend well beyond the unit itself. Consequential damages to other system components and the operational impact of lost production are rarely fully offset by warranty terms. Identifying a fault through timely DGA before it leads to failure is a materially better outcome than processing a warranty claim after one.
Summary:
- Early DGA testing can catch incipient faults before they escalate into irreversible damage or system-wide failures.
- Manufacturers often require DGA as a warranty condition — failure to follow the recommended testing schedule may void coverage.
- The first 30 days in service are the highest-risk window for detecting manufacturing defects through dissolved gas signatures.
- Fault prevention outweighs fault recovery — identifying a defect before failure avoids consequential damage and lost production, even when repairs are covered under warranty.
